1. Field of the Invention
The present invention concerns a filter and gas vent system intended to be incorporated in an ostomy bag during its manufacture.
2. Discussion of the Background
Ostomy patients are patients who have undergone a surgical procedure such as a colostomy or ileostomy with creation of an artificial anus, which is also called by extension a "stoma". They are then provided with a collecting bag which is made up of two walls of impermeable plastic material which are welded to each other about the perimeter of the bag. One of these walls includes an opening for collecting the matter coming from the stoma. This opening is surrounded by a cutaneous protector intended to adhere in a practically leaktight manner to the abdominal wall of the ostomy patient for the purpose of holding the bag in place.
The matter collected in the bag is accompanied by intestinal gases whose evacuation is necessary in order to avoid excessive inflation of the bag. However, it is expedient to maintain a minimum residual pressure inside the bag. The reason is that, if this maintenance is not done, the two walls of the bag could stick to each other, and this sticking would impede the admission of matter into the bag. A slight cushioning effect also increases comfort by preventing the transmission of external pressures, especially those of clothes, to the stoma, which remains sensitive. For this purpose, the bag is provided with a gas vent. The latter is arranged above the opening in the bag through which the matter enters, such that the fecal matter, falling under gravity to the bottom of the bag, does not obstruct the vent.
Moreover, some intestinal gases release a foul odor which is embarrassing for the patient and for those around him or her. The vents are therefore provided with a deodorizing filter placed in the path of the gases in such a way that the intestinal gases pass through it and are purified before leaving the bag. In the earliest filter and vent systems, the filter was simply placed on the vent hole formed in one of the walls of the bag, depending on the circumstances either on the outside or on the inside of the bag. Then, in order to reduce the manufacturing costs and at the same time to avoid any moves having to be made by the ostomy patients, who are sometimes elderly or handicapped, attempts were made to incorporate the filters in the bag at the very moment of manufacture of the latter.
From the number of incorporated systems of this kind, mention may be made of European Patent No. 68,964 in the name of Laboratories Biotrol. This system is in the form of a disc of filtering material protected by a film. It is held in the peripheral weld seam of the bag so as to straddle the latter, thereby forming a filter with direct passage. Its exit face can open directly to the outside of the bag or alternatively to the inside of a downstream chamber which forms an integral part of the bag, or a complementary part, with walls that can be perforated to form a vent.
This system was then improved, especially as regards the length of travel of the gases and thus as regards its duration of effective operation, by the system forming the subject of French Patent No. 2 615 099. This system is in the form of a flat band and is made up of an elongate filtering core held between two protective films welded to each other on either side of the core. It is arranged between the two walls of the bag so as to extend horizontally from one side edge of the bag to the other. It is held in the peripheral weld seam of the bag in the area of each of these edges. The ends of the filter are free of film, so that the core communicates with the outside of the bag. The gases pass into the core via a hole formed in the protective film at the center of the filter. They thus travel half the width of the bag before being released to the outside via the ends of the filter.
The filter according to French Patent No. 2 615 099 which has just been described does have a disadvantage, however. This disadvantage is that the material composing its core rubs along the perimeter of the bag. Now, it contains activated charcoal which can come loose and soil the clothes. When the patient showers, the activated charcoal particles axe driven off in even greater quantities. The ends of the filter additionally clog up, preventing the filter from functioning. The fact that it is an integral part of the bag means that it is necessary to discard the whole bag. Moreover, the liquid matter inside the bag can pass along the activated charcoal and seep out and thus soil the clothes, at the same time causing unpleasant odors. It is conceivable to close off the ends of the filter with removable caps, but this arrangement is no more satisfactory than the filters attached afterwards to the bag, the ostomy patients often being elderly and infirm. Thus, it is a problem to develop an incorporated filter and vent system in which the core of the filter remains isolated from the outside of the bag.